A vehicle such as a work machine, on- or off-highway truck, automobile, or other equipment has a brake operator device allowing an operator to control deceleration of the vehicle. The vehicle also has a transmission which allows the vehicle to be driven using one of several gear ratios, for desired torque and speed characteristics. Many vehicles include an Integrated Braking System (IBS), which uses a mechanical brake valve and a rotary position sensor associated with the brake operator device to detect a brake operator device angle position when the vehicle is in a higher gear.
Under IBS, the transmission is downshifted and/or neutralized to reduce dependence on the brakes to stop the machine. However, this configuration is subject to a deadband (no brake response within a predetermined initial portion of brake operator device travel) to facilitate the transmission-caused deceleration in the higher gears, with IBS active. Since the deadband cannot be adjusted during operation of a mechanical brake valve-equipped vehicle, the deadband reduces available brake operator device travel for braking in lower gears (when IBS is inactive). This reduced brake operator device travel results in lower resolution of the brake operator device and may cause an operator perception of less control over the brakes.
U.S. Pat. No. 5,105,923, issued Apr. 21, 1992 to Naonori Tizuka (hereafter referenced as '923) discloses an engine braking control system for an automatic transmission. The '923 device causes a downshift in response to engine braking requirements, vehicle speed, throttle opening, and brake operator device position. However, the transmission gear selected is not taken into account in '923, so the vehicle response cannot differ when the vehicle is traveling in different gears.
The present invention is directed to overcoming one or more of the problems as set forth above.